Ricoh A230, Service Manual, Page: 631 / 1134

IMAGE SCANNING
SM 21-3 A230/A231/A232
SCA
NNE
R KI
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A69
5
2.2 IMAGE SCANNING
The image data for the scanner comes from the Image Processing Unit (IPU) chip
on the Base Engine and Image Control Unit (BICU) board in the main machine
through the Mother Board (MB) of the expansion box. Most image processing for
the scanner is performed in the IPU. However, gamma patterns and dither patterns
which are stored in the RAM on the scanner board are used.
The 8-bit image data (in grayscale processing mode) from the IPU chip goes to the
Selector, where the data is divided into two image data signals: odd-pixel data and
even-pixel data. This is to match the data transfer speed between the input data
(20 MHz – grayscale processing mode) and the process speed in the scanner
Buffer Control (SBC) chips (10 MHz each). Then, filters and patterns are used to
process the data and the data is merged in the Multiplexer. The data is then sent
to the PC through the SCSI Controller.
1-bit data (in binary picture processing mode) is not divided into two data signal
and it will be used only the SBC 1 chip.
The image data is stored in the Memory Buffers (1 & 2). The total memory size is 2
MB. When the memory is full, the scanner will stop scanning until the memory is
empty. Then, the scanner will start scanning again.
S B U
I P U
B I C U
Selector
S B C 1
S B C 2
Multiplexer
S C S I
Contr
oller
M e m o r y
Buffer 2
M e m o r y
Buffer 1
Scanner Controller
M B S I B
8-bit data 1-bit data
P C